Manufacture of adhesives



106. COMPOSITIONS,

COATING OR PLASTIC.

77a WuNunu DiAinS 'PATENT OFFICE.

JAIES DONOVAN IALCOLHSON, OF WILKINSBUBG, IPENNSYLVANIA, ASSIGNOB, BY

IESNE ASSIGNMENTS, TO THE CONTAINER CLUB, OF CHICAGO, ILLINOIS, A COB- POBATION OF DELAWARE.

IANUFACTUBE OF ADHFSIVES.

Io Drawing.

To all whom it may concem Be it known that I, J AMES DONOVAN MAL- COLMSON, a citizen of the United States, residing at No. 199 Meade street, Wilkinsburg, in the county of Allegheny, State of Pennsylvania, have invented certain new and useful Improvements in the Manufacture of Adhesives; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as Wlll enable others skilled in the art to which it appertains to make and use the same.

Commercial silicatlei of soda (wateghglass) is lar ely used in t e art as an a esive as, for instance, in the paper boarmustr and particularly in the production of socalled corrugated bmrd, and the like. For

v I I. v0 mu 91018. Sillcate of soda possesses physical properties, which particularly adapt it to successful use, such as the requisite adhesive power, viscosity, speed of drying, degree of enetration (absorption), and flexibility w en dry. It is in large demand, and is used in a. great many manufacturing establishments throughout the country, so that the obtaining of the necessary supply and the question of transportation and the freight rates thereon, are of material importance to the arts in which it is used.

The present invention is based upon the discovery that the volume of commercial silicate of soda can be materially increased, mifiparativel small expense, without sacrificing any of t e original physical properties which make it of value as an adhesive; and even with the enhancing of certain of those properties, if, in any instance, it is considered appropriate to do so. The material to be added to the water glass, for the purpose of increasing its volume, is, moreover, readily obtainable and of relatively small cost, and the expense involved in inco rating it in the water glass is moderate,the apparatus appropriate for the purpose be' simple and economical in construction an operation.

Commercial silicate of soda or water lass consists mainly o y silicate oi sodium and h drated the 'iaaabin resent in't e mixture in a have ascertained that if there is aide to Specification 01' Letters Patent.

Patented May 31, 1921.

water glass will tolerate a relatively large quantity of the added brine without losing 1ts original properties. The brine should be ad e water glass slowl and at t e same time, the wa r g s s ou be constantly stirred so as tdpreyentathmsflhthng oftlf'TEEhfltiaint gelatingus silig a, which wouldot'herwise accumulate aiid coalesce at the bottom of the receptacle in a jelly-like layer. A further function of the stirring, is, moreover, to assist in the reversion to the colloidal state, of the lumps or clots of the elly-like silica referred to. The result is that after the necessary period of time has elapsed, the lumps or clots disappear, and the product is of an increased volume corresponding to the amount of brine added. The solution can be diluted with 20% or more of brine, and the resultant viscosity will nevertheless be ual to or even greater than that of the original water glass.

The most satisfactory results have been obtained by the additjgggfZOfi; by volume of brine containing from20 to 21% by weight of salt.

It is a characteristic of the invention that the viscosities, at the point nearest the original viscosity of the water glas, can be controlled very accurately by a very small change in the concentration of the added brine. This permits a manufacturer to determine what particular viscosity he de- 1 used, and while still preserving the other quahties of the adhesive practically unchanged. Furthermore, this concentration can be accurately controlled with a hydromeher, since at these concentrations, the hydrometer is very sensitive to even small ghanges in the amount of salt present in the rme.

It will be found that when 20% by volume of brine is added to the water glass, a viscosity somewhat in excess of the normal can be obtained by having the concentration at 21%, and that the viscosity can be lowered to and below the normal by decreasing the concentration from that percentage downwardly. Usually, it will not be desirable to decrease the concentration materially, if at all, below 20% for the reason that at lower degrees of concentration there is, in part, a

sacrifice of the adhesive properties of the product.

In making up the brine, it will suflice to merely add the correct weight of crude salt to the appropriate amount of water. The

specific gravty is then checked with an ordi-.

nary hydrometer, of the heavier than water style, reading from to 25 Baum, which will show very accurately the amount of salt in solution, if the solution has been well stirred.

It will be understood that instead of mak-' ing up the brine from sodium chlorid, an equivalent therefor may be employed, such as chlorid of otassium or a chlorid of the alka- Eme earth metals; but, in general, it Wlll not e advisa e to use a substitute for chlorid of sodium for the reason that it fully subserves the intended function and is not only contained impurities merely settling to the bottom.

Having thus described my invention, what I claim is:

1. The method of increasing the volume of water glass without impairin its adhesive properties, which comprises a ding brine to the water glass, and redissolving in the water glass the silica coagulated by the addition of brine; substantially as described.

2. The method of increasing the volume of water glass without impairin its adhesive properties, which comprises adding brine to the water glass, and re-dissolving in the water glass the silica coagulated by the addition of brine, stirring eing employed to prevent settling of the coa ulated silica, and for assisting its re-dissolvmg; substantially as described.

3. An adhesive, consisting of water glass whose volume has been increased by the addition of brine, and in which the silica coagulated by the addition of the brine has been re-dissolved; substantially as described.

4. An adhesive, consisting of water glass whose volume has been increased by the addition of brine, and in which the silica coagulated by the addition of the brine has been re-dissolved, the quantity of brine added being approximately 20% by volume of the water glass and containing about 20 to 21% by weight of salt; substantially as described.

In testimony whereof I afiix my signature.

JAKE DONOVAN IALCOLMSON. 

